This invention relates generally to systems for forming laminations used in electrical devices, such as those used in the windings for D.C. motor armatures or A.C. rotors and stators. More particularly, the present invention relates to a method and apparatus for automatically producing interlocked laminations from blanks, or strips.
Typically, laminations are created from continuous sheets that are fed through progressive cutting, punching, and bending steps in a tool and die assembly until the desired end configuration is obtained. Once cut to the desired configuration, laminations are typically stacked, or piled together to achieve the required thickness of laminations.
It is desirable to retain the laminations together in a stack of the desired height in some way so the stack of laminations can be moved together in order to undergo further processing.
Various methods and apparatus have been used to fasten the laminations together, including the use of tabs in the laminations which extend below a surface of the lamination and are inserted into a slot formed in the next adjacent lamination. As each lamination is cut out of the blank, or carrier strip, it is pushed out the end of the die and positioned adjacent to the next lower lamination in the stack. Typically, at least the bottom lamination in the stack has the interlock tabs removed to prevent a stack of laminations from becoming interlocked with another stack of laminations.
This method of securing laminations together works fairly well, but part of the assembly method must include a way to align each lamination coming out the end of the die with the laminations in the stack so that the tabs align with the slots in the adjacent lamination. This typically requires piling the disconnected laminations on a spindle, or in a barrel type mechanism that rotates the lamination until the tab is aligned with the slot on the adjacent lamination and drops into that slot. In many situations, once the stack has been made, additional processing must be done to compress the laminations together so the tabs are firmly seated in the slots in order to keep the stack secured together. This step of aligning the laminations in the stack is time-consuming, and often results in decreased output from the manufacturing process. Attempts to speed up this step generally result in an increased number of misaligned laminations, and therefore a higher number of rejected parts.
Accordingly, a continuing search has been directed to the development of a method which can increase the throughput of lamination stacks, while consistently providing stacks that are accurately aligned and properly secured.
Therefore, what is needed is an improved system and method for manufacturing and interlocking laminations.
Accordingly, the system of the present invention provides a method of interlocking a lamination that is still attached to the carrier strip to at least one lamination that has already been disconnected from the carrier strip. Performing this interlocking step while a lamination is still attached to the carrier strip eliminates the need for the extra step of having to align the laminations before they can be interlocked. Because the lamination being interlocked is still connected to the carrier strip, it is in a known, fixed position, and can be accurately aligned with the adjacent lamination. Elimination of the time-intensive step of aligning the laminations speeds up production throughput, and reduces failures due to misalignments.
One aspect of the present invention is a method for manufacturing lamination assemblies from a strip of laminate, wherein at least one first lamination and at least one second lamination are cut in the strip, with at least one hole cut in each first lamination and at least one interlock tab in each second lamination. The first lamination is detached from the strip, and the strip is then moved so that the second lamination, still attached to the strip, is positioned adjacent to the disconnected first lamination. The interlock tab on the second lamination, which is inserted through the hole on the second lamination, is bent so that the interlock tab contacts the side of the first lamination in the stack that is opposite to the side adjacent to the second lamination, interlocking the at least one first lamination and the second lamination. The second lamination, which is now interlocked to the at least one first lamination, is then disconnected from the strip.
Another aspect of the present invention is a method for manufacturing lamination assemblies from a strip of laminate, wherein at least one first lamination and at least one second lamination are cut in the strip, with at least one interlock tab on each second lamination. The first lamination is detached from the strip, and the strip is then moved so that the second lamination, still attached to the strip, is positioned adjacent to the disconnected first lamination. The interlock tab on the second lamination is bent around the periphery of each first lamination and the interlock tab is crimped such that it contacts the side of the first lamination in the stack that is opposite to the side adjacent to the second lamination, interlocking the at least one first lamination and the second lamination. The second lamination, which is now interlocked to the at least one first lamination, is then disconnected from the strip.
Yet another aspect of the present invention is a tool and die apparatus for manufacturing an interlocked stack of laminations from a strip of material, comprising a series of dies and punches. At least one die is used for cutting holes in a first lamination, removing the material that is cut. At least one die is used for cutting at least one hole in a second lamination. A die is used for parting at least one first lamination from the strip of material. A stacker positions the second lamination adjacent to the first lamination parted from the strip of material. A punch presses the material from the hole on the second lamination into the corresponding hole on each first lamination and bends the material against the side of the first lamination that is opposite to the side adjacent to the second lamination. A die parts the second lamination, now interlocked to the first lamination, from the strip of material.
In yet another aspect of the present invention a tool and die apparatus is used for manufacturing an interlocked stack of laminations from a strip of material, comprising a series of dies and punches. At least one die is used for cutting at least one first lamination. At least one die is used for cutting at least one second lamination having at least one tab extending from the periphery. A die is used for parting at least one first lamination from the strip of material. A stacker positions the second lamination adjacent to the first lamination parted from the strip of material. A punch bends the tab on the second lamination next to the periphery of each first lamination and against the side of the first lamination that is opposite to the side adjacent to the second lamination. A die parts the second lamination, now interlocked to the first lamination, from the strip of material.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.